You could have something slightly granular: what I'm immediatly picturing is something like scrollbars for each area of content. For example some words might have a great deal of sexual content, while other may only be mature in terms of violence. In this approach, the one who pick the content can figure out whether it works for them based on the severity of any given factor.
Sources of inspiration: Interestingly enough, privacyfeatures as a firefox addon. You can toggle different features on and off to suit your needs. This is something I'm envisioning for ratings systems.